<template>
  <div class="drag" ref="dragDiv">
    <div class="drag_bg"></div>
    <div class="drag_text">{{confirmWords}}</div>
    <div ref="moveDiv" @mousedown="mouseDownFn($event)" :class="{'handler_ok_bg':confirmSuccess}" class="handler handler_bg" style="position: absolute;top: 0px;left: 0px;"></div>
  </div>
</template>

<script>
export default {
  data(){
    return {
      beginClientX: 0,           /*距离屏幕左端距离*/
      mouseMoveState: false,     /*触发拖动状态  判断*/
      maxWidth: '',               /*拖动最大宽度，依据滑块宽度算出来的*/
      confirmWords: '向右拖动滑块验证',   /*滑块文字*/
      confirmSuccess: false           /*验证成功判断*/
    }
  },
  methods: {
    //mousedown 事件
    mouseDownFn:function (e) {
      if(!this.confirmSuccess){
        e.preventDefault && e.preventDefault();   //阻止文字选中等 浏览器默认事件
        this.mouseMoveState = true;
        this.beginClientX = e.clientX;
      }
    },
    //验证成功函数
    successFunction(){
      this.confirmSuccess = true;
      this.confirmWords = '验证通过';
      if(window.addEventListener){
        document.getElementsByTagName('html')[0].removeEventListener('mousemove',this.mouseMoveFn);
        document.getElementsByTagName('html')[0].removeEventListener('mouseup',this.moseUpFn);
      }else {
        document.getElementsByTagName('html')[0].removeEventListener('mouseup',()=>{});
      }
      document.getElementsByClassName('drag_text')[0].style.color = '#fff';
      document.getElementsByClassName('handler')[0].style.left = this.maxWidth + 'px';
      document.getElementsByClassName('drag_bg')[0].style.width = this.maxWidth + 'px';
    },
    //mousemove事件
    mouseMoveFn(e){
      if(this.mouseMoveState){
        let width = e.clientX - this.beginClientX;
        if(width>0 && width<=this.maxWidth){
          document.getElementsByClassName('handler')[0].style.left = width + 'px';
          document.getElementsByClassName('drag_bg')[0].style.width = width + 'px';
        }else if(width>this.maxWidth){
          this.successFunction();
        }
      }
    },
    //mouseup事件
    moseUpFn(e){
      this.mouseMoveState = false;
      var width = e.clientX - this.beginClientX;
      if(width<this.maxWidth){
        document.getElementsByClassName('handler')[0].style.left = 0 + 'px';
        document.getElementsByClassName('drag_bg')[0].style.width = 0 + 'px';
      }
    }
  },
  mounted(){
    this.maxWidth = this.$refs.dragDiv.clientWidth - this.$refs.moveDiv.clientWidth;
    document.getElementsByTagName('html')[0].addEventListener('mousemove',this.mouseMoveFn);
    document.getElementsByTagName('html')[0].addEventListener('mouseup',this.moseUpFn)
  }
}
</script>
<style scoped>
.drag{
  position: relative;
  background-color: #e8e8e8;
  width: 100%;
  height: 40px;
  line-height: 40px;
  text-align: center;
  border: 1px solid #ccc;
  border-radius: 4px;
}
.handler{
  width: 40px;
  height: 38px;
  border: 1px solid #ccc;
  border-radius: 4px;
  cursor: move;
}
.handler_bg{
  background: #fff url("") no-repeat center;
}
.handler_ok_bg{
  border-top-left-radius: 0;
  border-bottom-left-radius: 0;
  background: #fff url("") no-repeat center;
}
.drag_bg{
  background-color: #7ac23c;
  height: 38px;
  width: 0px;
  border-radius: 4px 0 0 4px;
}
.drag_text{
  position: absolute;
  top: 0px;
  width: 100%;text-align: center;
  -moz-user-select: none;
  -webkit-user-select: none;
  user-select: none;
  -o-user-select:none;
  -ms-user-select:none;
}
</style>
